1 //===-- Optional.h - Simple variant for passing optional values ---*- C++ -*-=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file provides Optional, a template class modeled in the spirit of
11 // OCaml's 'opt' variant. The idea is to strongly type whether or not
12 // a value can be optional.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_ADT_OPTIONAL
17 #define LLVM_ADT_OPTIONAL
28 explicit Optional() : x(), hasVal(false) {}
29 Optional(const T &y) : x(y), hasVal(true) {}
31 static inline Optional create(const T* y) {
32 return y ? Optional(*y) : Optional();
35 Optional &operator=(const T &y) {
41 const T* getPointer() const { assert(hasVal); return &x; }
42 const T& getValue() const { assert(hasVal); return x; }
44 operator bool() const { return hasVal; }
45 bool hasValue() const { return hasVal; }
46 const T* operator->() const { return getPointer(); }
47 const T& operator*() const { assert(hasVal); return x; }
50 template<typename T> struct simplify_type;
53 struct simplify_type<const Optional<T> > {
54 typedef const T* SimpleType;
55 static SimpleType getSimplifiedValue(const Optional<T> &Val) {
56 return Val.getPointer();
61 struct simplify_type<Optional<T> >
62 : public simplify_type<const Optional<T> > {};
64 /// \brief Poison comparison between two \c Optional objects. Clients needs to
65 /// explicitly compare the underlying values and account for empty \c Optional
68 /// This routine will never be defined. It returns \c void to help diagnose
69 /// errors at compile time.
70 template<typename T, typename U>
71 void operator==(const Optional<T> &X, const Optional<U> &Y);
73 /// \brief Poison comparison between two \c Optional objects. Clients needs to
74 /// explicitly compare the underlying values and account for empty \c Optional
77 /// This routine will never be defined. It returns \c void to help diagnose
78 /// errors at compile time.
79 template<typename T, typename U>
80 void operator!=(const Optional<T> &X, const Optional<U> &Y);
82 /// \brief Poison comparison between two \c Optional objects. Clients needs to
83 /// explicitly compare the underlying values and account for empty \c Optional
86 /// This routine will never be defined. It returns \c void to help diagnose
87 /// errors at compile time.
88 template<typename T, typename U>
89 void operator<(const Optional<T> &X, const Optional<U> &Y);
91 /// \brief Poison comparison between two \c Optional objects. Clients needs to
92 /// explicitly compare the underlying values and account for empty \c Optional
95 /// This routine will never be defined. It returns \c void to help diagnose
96 /// errors at compile time.
97 template<typename T, typename U>
98 void operator<=(const Optional<T> &X, const Optional<U> &Y);
100 /// \brief Poison comparison between two \c Optional objects. Clients needs to
101 /// explicitly compare the underlying values and account for empty \c Optional
104 /// This routine will never be defined. It returns \c void to help diagnose
105 /// errors at compile time.
106 template<typename T, typename U>
107 void operator>=(const Optional<T> &X, const Optional<U> &Y);
109 /// \brief Poison comparison between two \c Optional objects. Clients needs to
110 /// explicitly compare the underlying values and account for empty \c Optional
113 /// This routine will never be defined. It returns \c void to help diagnose
114 /// errors at compile time.
115 template<typename T, typename U>
116 void operator>(const Optional<T> &X, const Optional<U> &Y);
118 } // end llvm namespace